I...don't think battles should be considered "dragging" on a battle shounen,you know?
Of course the obvious way of things is that some of the enemies are going to be fodder.That's just natural,and it's a part of it.
It's like playing an RPG and getting annoyed because every single boss fight drags the plot.It's truth,but the battles are a important part of the game,even the most obvious ones where the main characters can't lose.
And even if you can predict the outcome of a battle,that's hardly all there is to it.If you think that way,then you just don't like the battles at all,but you shouldn't complain since it's one of the most important aspects of this genre.